The chemical amplification-type positive resist composition is a pattern-forming material of forming a pattern on a substrate by producing an acid in the exposed area upon irradiation of radiation such as far ultraviolet light and due to a reaction using this acid as the catalyst, causing the active radiation-irradiated part and non-irradiated part to change in the solubility in a developer.
In the case of using a KrF excimer laser as the exposure light source, a resin having small absorption in the region of 248 nm and having a basic skeleton of poly(hydroxystyrene) is primarily used as the main component and this is an excellent system of forming a good pattern with high sensitivity and high resolution as compared with conventional naphthoquinonediazide/novolak resin systems.
In the case of using a light source of emitting light at wavelengths shorter than that, for example, in using an ArF excimer laser (193 nm) as the light source, a satisfactory pattern cannot be formed even by the above-described chemical amplification system because the compound having an aromatic group substantially has large absorption in the region of 193 nm.
In order to solve this problem, a resist containing a resin having an alicyclic hydrocarbon structure has been developed for use with an ArF excimer laser.
For example, Patent Document 1 (JP-A-10-254139 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) describes use of a solvent comprising a mixture of a linear ketone and at least one member selected from a cyclic ketone, a propylene glycol monoalkyl ether acetate and an alkyl 2-hydroxypropionate with an attempt to provide a radiation-sensitive resin composition excellent in the transparency to radiation, dry etching resistance, film thickness uniformity, adhesion to substrate, sensitivity, resolution, developability and the like.
Patent Document 2 (JP-A-2002-229192) is proposing to use a specific compound having a cyclic sulfonium structure and a benzene or naphthalene ring as the radiation-sensitive acid generator with an attempt to provide a radiation-sensitive resin composition having high transparency to far ultraviolet ray and at the same time, excellent in the sensitivity, resolution, pattern shape and the like.
Patent Document 3 (JP-A-2001-142212) discloses a resist composition improved in the sensitivity, resolution, adhesion to substrate, and edge roughness of pattern, which is a composition containing a specific resin having an alicyclic structure and a specific solvent such as propylene glycol monomethyl ether acetate.
However, a fine pattern of 120 nm or less is very difficult to form by a contact hole process and application of a technique of shrinking the pattern by a thermal flow process is being studied. Those conventional resist compositions suffer from generation of cracking at the thermal flow process or have a problem in the dry etching resistance.
Also, various compositions using a resin containing an adamantyl group having a hydroxyl group have been heretofore proposed, but when these compositions are applied to the thermal flow technique, cracking is sometimes generated on the resist surface at the thermal flow baking.
[Patent Document 1]
JP-A-10-254139
[Patent Document 2]
JP-A-2002-229192
[Patent Document 3]
JP-A-2001-142212